Hoogerland, Maarten

Wednesday Aug 28, 2013
Time: 14:00
Place: ETH Science City, HPF G6
Host: Tobias Donner/Tilman Esslinger

A Quantum Ratchet showing directional motion in absence of a directional force

Maarten Hoogerland
University of Auckland, New Zealand

A Brownian ratchet, which gives directional motion in absence of a directional force, is familiar from Feynman's lectures on physics, where he shows that it will not work. We observe quantum ratchet behavior in the delta-kicked rotor system, which is a classically chaotic system which we study in the quantum domain.  We show clear directed momentum current in the absence of a directional force. We use a Bose-Einstein Condensate as the source of ultra-cold atoms, and employ asymmetric phase modulation in the kicks, whilst the narrow momentum distribution of the atoms allows us to address individual island structures in phase space. We characterize and connect our experiments to ε–classical theory.